4702-17-4Relevant academic research and scientific papers
Diastereoselective radical addition to dehydroalanine derivatives of pantolactone
Yim, Anne-Marie,Vidal, Yves,Viallefont, Philippe,Martinez, Jean
, p. 503 - 510 (2002)
The diastereoselective synthesis of α-amino acids by radical addition to dehydroalanine derivatives of pantolactone using the stannane method both in the presence and absence of Lewis acid catalysts is reported. The absolute configuration of the newly-generated stereogenic center is highly dependent on the nature of the added radical. Acid hydrolysis afforded the amino acids with excellent yields and without racemization. This approach constitutes a novel method for the asymmetric synthesis of α-amino acids by a radical pathway.
Iron-Catalyzed Diastereoselective Synthesis of Unnatural Chiral Amino Acid Derivatives
Zhang, Hao,Li, Haifang,Yang, Haijun,Fu, Hua
supporting information, p. 3362 - 3365 (2016/07/26)
An iron-catalyzed diastereoselective synthesis of unnatural chiral (S)-α-amino acids with γ-quaternary carbon centers has been developed. The protocol uses inexpensive iron salt as the catalyst, readily available 2-phthaloyl acrylamide and alkenes as the starting materials, and phenylsilane as the reductant, and the reactions were performed well in mixed solvent of 1,2-dichloroethane and ethylene glycol at room temperature. The method shows some advantages including simple and wide substrates, mild conditions, high diastereoselectivity, and easy workup procedures.
Modular Access to Substituted Azocanes via a Rhodium-Catalyzed Cycloaddition-Fragmentation Strategy
Shaw, Megan H.,Croft, Rosemary A.,Whittingham, William G.,Bower, John F.
supporting information, p. 8054 - 8057 (2015/07/15)
A short entry to substituted azocanes by a Rh-catalyzed cycloaddition-fragmentation process is described. Specifically, exposure of diverse N-cyclopropylacrylamides to phosphine-ligated cationic Rh(I) catalyst systems under a CO atmosphere enables the directed generation of rhodacyclopentanone intermediates. Subsequent insertion of the alkene component is followed by fragmentation to give the heterocyclic target. Stereochemical studies show, for the first time, that alkene insertion into rhodacyclopentanones can be reversible.
Total synthesis of the antitumor antibiotic (±)-streptonigrin: First- and second-generation routes for de novo pyridine formation using ring-closing metathesis
Donohoe, Timothy J.,Jones, Christopher R.,Kornahrens, Anne F.,Barbosa, Luiz C. A.,Walport, Louise J.,Tatton, Matthew R.,O'Hagan, Michael,Rathi, Akshat H.,Baker, David B.
, p. 12338 - 12350 (2014/01/17)
The total synthesis of (±)-streptonigrin, a potent tetracyclic aminoquinoline-5,8-dione antitumor antibiotic that reached phase II clinical trials in the 1970s, is described. Two routes to construct a key pentasubstituted pyridine fragment are depicted, both relying on ring-closing metathesis but differing in the substitution and complexity of the precursor to cyclization. Both routes are short and high yielding, with the second-generation approach ultimately furnishing (±)-streptonigrin in 14 linear steps and 11% overall yield from inexpensive ethyl glyoxalate. This synthesis will allow for the design and creation of druglike late-stage natural product analogues to address pharmacological limitations. Furthermore, assessment of a number of chiral ligands in a challenging asymmetric Suzuki-Miyaura cross-coupling reaction has enabled enantioenriched (up to 42% ee) synthetic streptonigrin intermediates to be prepared for the first time.
Total synthesis of (±)-streptonigrin: De novo construction of a pentasubstituted pyridine using ring-closing metathesis
Donohoe, Timothy J.,Jones, Christopher R.,Barbosa, Luiz C. A.
supporting information; experimental part, p. 16418 - 16421 (2011/11/29)
The synthesis of the potent antitumor agent (±)-streptonigrin has been achieved in 14 linear steps and 11% overall yield from ethyl glyoxalate. The synthesis features a challenging ring-closing metathesis reaction, followed by elimination and aromatization, to furnish a key pentasubstituted pyridine fragment.
